I have heard tracks in terminals referred to as "1 Relay" or "3 Relay". This seems to have been a common designation on the PRR and successor lines. One place they exist is in Altoona at CP-Works.
I have tried searching the web for an answer but to no avail. My best guess is that they were called relay tracks or relay yards because they were temporary stopping points where one crew relayed the train to another, since they seem to exist at locations that are or once were division points. Since power and cabooses were usually changed out at division points they would need a place to clear the main (if the train wasn't being reclassified in the yard) while these activities took place.
Can anyone confirm this or explain the origin/meaning? Also, is the term in common use on other railroads?
Note: I'm not referring to "relay rail" which I know is rail pulled up from one location and "relayed" elsewhere to replace older or worn out rail.
Below is a diagram of the current Norfolk Southern trackage in Altoona,PA found at www.parailfan.com
It shows tracks designated as 1 Relay, 2 Relay and 3 Relay at Works in the center of the diagram.
